Adhesive bonding, the new trend in Automotive
Adhesive bonding applications are becoming more dominant in AWL machines. Adhesive bonding has taken a huge leap and provides the next generation of joinings with an answer to the shift towards lightweight.
When thinking of car components and assembling such parts, most people imagine welding machines, rivets, bolts and screws. You might be surprised to learn that more and more companies use glue to join some parts together in modern vehicles. These adhesives are composed of advanced materials called epoxies and can join almost any material to any surface.
The joint is able to endure a wide range of temperature extremes; a requisite, as a car is subjected to all kinds of weather.
Body parts, seats, doors, tailgates and hoods are examples of car components where case adhesive bonding is regularly applied.
Drivers for change
Reduction of weight is one of the main drivers for using these applications. Welding and bolting require a certain minimum plate thickness. With adhesives you can simply use thinner steel (0.4 mm), or even switch to alternative materials, such as aluminium or carbon fibres.
Strength versus flexibility
The application of adhesive bonding also offers a very high stiffness and good crash properties due to the continuous joint. In fact, most adhesives form a bond that is stronger than the bonded materials. Adhesives have the ability to flex and absorb an impact and distribute it across the whole surface area.
Our scope
The scope of adhesives is very large. At AWL we mostly integrate machines for anti-flutter adhesives, sealant adhesives and constructive adhesives. This last one particularly has our focus. Constructive adhesives can be divided into 1K and 2K.
Both are made of chemicals called epoxies, which consists of two parts, a resin and a catalyst. When these two components are combined a chemical reaction takes place.
1K vs 2K
For 1K adhesives this reaction doesn’t take place until the material is heated to 180°. This is commonly achieved during the e-coating of the product. In addition 1K epoxies are able to absorb small quantities of oil, therefore degreasing is not necessary. As adhesive doesn’t cure until heated it does not harden inside the dispensing equipment.
2K epoxies cure at room temperature, therefore an autoclave is not necessary. This composition is ideal for products that have no post-production treatments.
Depending on the characteristic of the load, you can decide to apply a very strong but ridged adhesive or a more flexible, less strong adhesive.
Our experience
Over the years AWL has completed several projects containing adhesive bonding applications. We expect that more and more customers will use adhesive bonding in the future as the focus in the automotive industry lies on weight reduction, comfort and safety. More and more products will be made of lightweight combinations where the interconnections will be glued, creating a strong, light and shock absorbent surface area.
Hybrid processes
Often adhesive bonding is combined with spot welding or clinching in order to allow the adhesive to harden and to ensure that all parts are properly connected.
Preconditions with adhesives
There are a number of preconditions that must be taken into account to ensure the quality of the bonding process:
The single parts. Parts must be relatively clean and there should be sufficient space to apply the adhesive.
The adhesive itself. The correct adhesive composition has to be selected depending on the product and the finishing process.
Adhesive dispensing equipment. Depending on the adhesive, the proper adhesive dosage equipment and application head must be selected. The application head can also be mounted on a robot.
Quality. A camera station can be installed to check if the adhesive is applied according to the specifications.